Creating a Bode Plot

A Bode Plot typically is used to display the frequency response of a linear, time-invariant system. Bode plots consist of a magnitude plot stacked above a phase plot. The stacked plots share a common X-axis scale.

• The Bode magnitude plot is a graph of log magnitude (gain) versus log frequency. The gain values by default are expressed in decibels.
• The Bode phase plot is a graph of phase angle versus log frequency. The phase angle by default is expressed in degrees.
  Note:

  You must define an AC analysis setup before attempting to create a Bode plot.

Follow this procedure to create a Bode plot:

1. Select Twin Builder >  Results > Create Standard Report > Bode Plot. The Report dialog box appears.
2. In the Context section, make selections from the following field or fields, depending on the design and solution type.
   • Solution – Lists the available solutions, whether sweeps or adaptive passes. Select AC:AC.
   • Domain – Select Sweep.
   • Optimetrics setup – Lists all defined Optimetrics analysis setups.
   • Select Quantities – Click to open the Select Quantities dialog box in which you can select additional quantities for plotting.

3. On the Trace tab, specify the information to plot:
   1. For the Primary Sweep field, specify the quantity to plot along the X-axis in one of the following ways:
      • Select a sweep variable F (frequency) from the drop-down list.
      • If sweeps are available, click to select sweeps. The quantity is plotted against the primary sweep variable listed.
   2. For the X field, select the Default check box to ensure that frequency is plotted along the X-axis.
   3. In the Category list, select the type of information to plot along the Y-axis.
   4. In the Quantity list, select the value to plot along the Y-axis.
   5. Optionally, in the Function list, select the mathematical function to be applied to the quantity to plot.

      The Signal field displays the currently specified Quantity and Function that will be plotted along the Y-axis. You can edit this field directly.

      Note:

      The text color shows whether the expression is valid (blue for valid expressions; red for invalid).

   6. Range Function – Click to open the Set Range Function dialog box. This applies the currently specified quantity and function.
4. Optionally, on the Families tab, confirm or modify the sweep variables to plot.
5. Click New Report.

This creates a new Bode plot in the Project tree, displays the plot with the defined trace, and enables the Add Trace button on the Report dialog box.

The function of the selected quantity is plotted against the swept variable values or quantities you specified on x-y magnitude and phase graphs. The plot is listed under Results in the Project tree and the traces are listed under the plot. When you select the traces or plots, their properties display in the Properties dialog box. You can edit these properties directly to modify the plot.

6. Optionally, add another trace to the plot by following the procedure above, using Add Trace rather than New Report.

Related Topics 

Sweeping a Variable

Working with Traces

Delta Markers in 2D Reports

Modifying Background Properties of a Report